The SCOR-A program concerns the Early Natural History of Atherosclerosis and Essential Hypertension and includes both clinical and experimental research. The clinical research is studying 5,000 children in a well defined biracial population for cardiovascular risk factor variables, to determine the distribution and prevalence, interrelationship, and time-course changes of the risk factors. Serum lipids and lipoproteins, blood pressure, selected anthropometric measurements, and other variables - tobacco usage and fasting blood glucose and insulin - are under study. The epidemiologic design provides cross-sectional and longitudinal observations since changes over time are critical aspects of the program in an effort to predict future hypertension and hyperlipoproteinemia and the occurrence of multi-risk factors. "Tracking" of the risk factor data is noted and indicates the merit of studying cardiovascular risk at an early age. Special sub-studies related to hypertension and hyperlipoproteinemia show racial differences which have implications for underlying biological mechanisms contributing to levels of risk factors. The experimental research includes nutrition studies on non-human primates to develop models of hypertension and hyperlipoproteinemia. A high sucrose intake has resulted in an exaggeration of the effect of oxogenous cholesterol on serum lipoproteins and on a salt induced hypertension. The chemistry of the arterial wall is also being studied to explore the role of proteoglycans in atherosclerosis and the biological properties of these macromolecules.